Post # 1
I’ve been reading the posts for a long time and am finally writing my own.
I know I want to get a moissanite engagment ring, and I know I want it to be an oval. What Im confused about is what size to get. I want to ring to be equivalant to 1 carat. On Moissanite Co. that would be a 7x5mm or .94, however I went to a jewlery store and saw a .86 oval diamond and it measured 8×5, which would mean the moissanite that supposed to be larger, would be smaller. To add to my confusion Asha rates their 7x5mm as a .75.
I know Asha and Moissanite dont work on the same scale as diamonds because they weigh differently, but I thought the mm sizes were supposed to be universal? No?
Post # 3
The difference could be the depth of the stone, maybe? You could, conceivably, have 2 stones that are the same dimensions on their face but be cut differently on the bottom for whatever reason, thus affecting the weight.
Not sure how *plausible* that is, but it’s logical.
Post # 4
I “think” that carats are the weight (total carat weight), and that can vary depending on the cut.
So obviously the mm sizes should be universal, but the weights may still be different (as PP said).
Post # 5
Carat weight and size (mm) are two different things. A one carat round brilliant diamond for example, may be cut very deep, leaving the bulk of the carat weight on the bottom of the stone, thus making it “face up” small. Similarly, a one carat round brilliant diamond may be cut too shallow, causing it to face up larger than it actually is. Ideally, the depth and table (top) should be “ideal” proportions to allow for maximum brilliance.
Aside from the table (top of the diamond) and the pavilion (the bottom part of the diamond), there is also a girdle (the “rim” that is between the table and the pavilion). This is another area that may or may a varying percentage of the diamonds weight.
Ovals may be far more confusing. I believe that the ideal table ratio (L X W) for an oval should be between around 1.35 and 1.45. That said, some people (myself included) prefer ovals that are shorter and fatter (around a 1.25-1.3 ratio), while others may prefer longer and thinner ovals (perhaps a ratio of 1.5).
Using diamonds as an example, you may see an oval diamond that weighs .85ct and is 8 X 5 (diamond A), and a .85ct diamond that measures 7 X 5 (Diamond B). Diamond A will have a lesser percentage of its carat weight coming from the bottom and more coming from the table whereas diamond B will have more weight on the bottom. Diamond A will also appear more elongated (L/W ratio of 1.6) while diamond B will appear a bit shorter and fatter in comparison to diamond A. Diamond B’s L/W ratio is 1.4.
Asha’s, Moissy’s, and Diamonds have different chemical compositions and thus have slightly different weights for their carat size.
I wouldn’t worry so much about the carat weight as much as the size/dimensions you prefer for your finger.
Hope this helps!